Thermostatic device



Sept- 29, 1935@ M. o. SNEDIKER THERMOSTATIC DEVICE I mm mm Filed July 13, 955

IIIH

IIHI IH Patented Sept. 29, 1936 UNITED STATES THERMO STATIC DEVICE Morton O. Snediker, Chicago, Ill., assignor to The Powers Regulator Company, Chicago, Ill., a corporation of Illinois Application July 13, 1935, Serial No. 31,188

9 Claims.

My invention relates to thermostatic devices and particularly to devices of that character used in connection with fluid-filled bulbs.

A difficulty encountered in devices of the type described is in their operation relative to the fluid used in the thermo-sensitive bulb.

In these devices the bulb andv instrument are joined by capillary tubing of more or less length dependent on the required conditions, and where lo the bulb and tube are solid iilled the temperature conditions reliected by the bulb are modified somewhat by variations in temperature in the space separating the bulb and instrument. This interferes with the accurate regulation that would 15 otherwise be secured. By solid filled" I refer to the arrangement in which the bulb and tube are filled with anon-volatile liquid, molecular expansion being relied upon as the means for reilecting temperature variations. Where a volatile liquid is employed for indicating the thermal effect, the modifying action of the temperature of the space intervening between the bulb and instrument is much less noticeable and for practical purposes ne'ed not be taken into the consideration, except in very unusual cases; this for the reason that the mass of a solid liquid in one case and of a tenuous vapor in the other case, is widely different and the heatabsorption and dissipation capacity -of the two is practically 30 in proportion to their respective masses.

However a difficulty arises in the use of the vapor filled device that is overcome in the instrument here disclosed; that is, the vapor pressure does not increase progressively in proportion to 35 increases in temperature, but is cumulative according to a known scale. This being true, it has been necessary to provide for corresponding variations in the scale of adjustment and of the recording device in case one is used in connection 4o with the instrument.

The instrument here disclosed serves to automatically compensate for the known Vvariations in the vapor pressure relative to different temperatures and thus to eiect a uniform movement,

45 per degree of heat change, of the valve that controls the regulating fluid; it also enables the use of an adjusting member in which the graduations are uniform throughout the range of control for which the instrument is designed.

50 A further advance in the art of constructing instruments such as here disclosed, is in the means for varying the cycle of the instrument. Instruments of this type are either gradual acting or positive acting. In the gradual acting type the 55 control valve opens very gradually, the speed of v determined ideal.

opening being determined in the design of the machine, the arrangement being such that a full opening of the heat supply valve is not brought about for some period of time after the opening movement begins. In the positive or quick acting type, the construction is such that the heat control valve is completely opened and completely closed in practically one movement. In constructions Where the latter type is desired, it is irequently impossible to avoid hunting; that is relatively frequently opening and closing of the valve when the temperature is at or near the pre- In the instrument here disclosed, I provide for a full range of adjustment from quick acting at the one extreme, to very gradual action at the other extreme. As a result, the same instrument may be used, not only for both types of regulation, but also in cases where the user may, in order to secure a desired result, Wish to adjust the instrument while in service to effect the ideal action. Heretofore it has frequently been necessary to experiment with successive instruments in order to meet conditions that could not be anticipated.

Further objects and advantages of the con- 25 struction will be pointed out in connection with the following description:

The invention will be more readily understood by reference to the accompanyingdrawing, in which; 39

Fig. 1 is a face view, with the cover removed, of apparatus constructed in accordance with my invention; and,

Fig. 2 is a view taken at right angles on the center line of Fig. l, some of the parts being shown in section and others in elevation in order to more clearly show the construction.

The instrument is intended to be actuated by means of a conventional bulb Ill through an armored capillary tube II, the tube beingcon- 40 nected to the interior of-a bellows I2. .The bellows is mounted on the cross piece I3 of the instrument frame, indicated generally by the numeral I4. A second length of tube I5 extends from the bellows upwardly to a dial thermometer I6. This forms no part of the present invention, but is illustrated merely to show that without correction the pressures developed are not proportional to the increase in temperature. This occurs where the bulb I0 contains a volatile liquid. It will be seen that the graduations at one extreme of indication on the thermometer dial are very -closely spaced, while those at the other extreme are Widely spaced.

All instruments of the type here illustrated should be provided with a means for manual adjustment over a specified range and this is accomplished by the use of an adjusting screw carrying a dial of some kind with graduations thereon, the graduations being arranged to correspond to variations in the temperature of the space ormediurn that is to be controlled. Thus it is desirable from the standpoint of the user that such graduations should be uniform throughout the range of adjustlment; that is, an equal space on the scale should correspond to an equal change of adjustment of the instrument. However, in the absence of compensating means such as here disclosed, the graduations on the adjustment dial would, in case a volatile fluid is used for regulation, be very closely spaced at one extreme and very widely spaced at the other extreme. To enable the use of a dial or drum having equal spaced graduations or markings thereon, and to effect a uniform movement, per degree of heat change, of the Valve that controls the regulating iluid,1 provide the following mechanism.

Mounted on brackets ll-l8 and carried by a cross shaft i9 is a lever arm 20 having ears 2l through -which the shaft i9 extends and provided with projections 22--23 that provide bearings for a shaft 24. On the lower end of the shaft, a drum 25 is mounted, being held in place by means of a set screw 26, the drum carrying a dial having graduaticns 21 thereon. It will be noted that the graduations are equally spaced. The extreme lower end of the shaft 2li is squared as indicated at 28 to facilitate engagement by a key for rotation of the shaft. A spring 29 is interposed between the projection 22 and the drum in order to insure a certain amount of frictional resistance to turning.

At a point between the two projections, 22-23, the shaft is of cylindrical form, and arranged on the cylinder is a helix or thread 3l),k of substantially uniform height from end to end.

The arm 20, with the parts carried thereby, is actuated by and is in contact with the bellows l2, through a screw 3l, seated in the arm and having a knurled head 32. This screw is used for initial or primary adjustment of the parts.

The movement of the bellows is transmitted through the rocking arm 2D and its associated parts including the helix Bil, to an aimiliary arm 33, the head 34 of which is slotted as at 35 to bear over a shaft 36. This shaft is carried by brackets 3l, formed on the main frame M.. The lower end of the arm 33 bears against an adjusting screw 3S carried at the lower end of the main rocker arm, which is likewise pivoted on the shaft A36. The lower end 39 of the rocker arm carries a heavy flat spring d, the upper end of which overlies the head 34 of the auxiliary arm 33. The arrangement is such that in case the adjusting screw is rotated to a low'temperature position with the parts in such position that this would otherwise entail a strain or breakage of some of the parts, the spring @lll will permit the auxiliary arm to be moved, by reason of the slots 535, to the desired position.

The upper end ll of the main arm carries screw B2 to the lower .end of which is connected the controlling valve stem t3 for the air under pressure, a spring M tending to separate the valve member from the seat carried by the valve body $5. The screw is provided for primary adjusting purposes.

By reference to Fig. 1 the air passages will be accept/e understood. A fluid under uniform pressure of about 15 pounds per square inch is supplied through the gage fitting il@ and delivered to a passage dll in the frame casting. A restriction screw Q8 controls the delivery of the fluid to the valve d5 which is in effect a leak valve. The passage i9 in the casting delivers the fluid to the outlet gage fitting 50 and from thence to a heat controlling valve in the usual manner. Thus es the valve t5 is closed, the pressure is permitted to build up in the outlet passage and the heat valve is actuated. As the valve l5 is opened, the air that passesthe restriction screw is permitted to waste and the heat valve is not affected.

The cycle correction means that forms an important part of this invention includes a passage 5l in the casting that is open to the passage lil and'communicates with a small bellows or diaphragm 52. Mounted in the upper end @l of the main arm is a screw 53, the lower end of which is positioned adjacent to the center of the bellows 52. As the screw is rotated its lower or inner end is moved toward or away from the face of the bellows 52. When in an extreme position the screw will be backed away from the bellows to an ci;- tent that the bellows has no effect on the operation of the arm. A pointer Lid on the screw 53 cooperates with a dial 55 to indicate the position of the parts.

Dependent on the position of the adjusting screw 53 the pressure admitted into the outlet passage lil is effective on the bellows 52 to oppose the action of the main bellows l2 tending to induce quick action in opening or closing of the leak valve; in other words, with the screw 53 turned to a position where the bellows 52 has no effect on the operation, an expansion of the bellows l2 due to an increase in heat acts immediately to close the valve t5 and to shut the heat valve. However, with the screw 53 in other positions where the bellows 52 can act against the main arm, on an increase of heat the expansion of the bellows l2 will act to start to close the valve l5 and pressure will build up in the outlet line; this will be eective in the bellows 52 to resist further movement of the main arm, tending to close the valve Q5, and thereby to interrupt the action until further heat acting on the main bellows l2 serves to overcome the offsetting eiect or" the cycle adjustment bellows and permit complete closing of the heat valve.`

Thus, a complete range of adjustment from quick acting to very gradual action can be secured in the same instrument.

The operation or" the compensating device is as follows:

The helix which is carried by the arm 2@ is rotatable with the graduated drum, thus moving the point of contact between the helix and the auxiliary arm 33 and changing the leverage of the cooperating parts. In that connection it should be understood that the helix is used for convenience in order to secure a relatively long contact area that may be changed by rotation of an adjusting element such as the drum. Theoretically, the same iinal result would be secured ii? the liever was fixed and not angularly disposed, and instead of the helix a provision was made `for an infinite number of contact pieces of progressively less height from the top to the bottom as viewed in Fig. 2. In that case it would be necessary when an adjustment to another temperature was desired, to remove a contact piece and replace it by another of lesser or member corresponding to the member on which the helix is mounted. However, this would be utterly impractical and the provision of the helix with the inclined arm with which it cooperates provides an innite number of contacts, anyone of which may readily be secured by rotation of the helix and drum.

The reason for the angularity of the arm 33 will be explained.

As a premise it is stated that all volatile liquids commonly used for regulation of instruments of this type have a ratio of increase of vapor pressure per degree of heat that progressively increases; this for our purpose may be translated into terms of proportionate expansion of the bellows I2; as an example assuming 100 degrees as a base, then the amount of expansion at 200 degrees will be approximately as 4 is to l; in other words the pressure increase is not arithmetical but according to a known scale determined by test.

Let it be assumed also as a premise that the controlling valve 43 should move a predeterdistance per degree of heat change regardless of the temperature and regardless of the volatile liquid used for regulation. Therefore, if the expansion of the bellows for each degree of heat increase is twice as great at one temperature as at another, then the leverage through which the pressure acts on the valve should be adjusted so that the resultant movement of the valve is the same at both temperatures. This is accomplished in my structure by correlating the length of the arm 4I from its pivot 36'with the pitch of the helix; so that, for example, if the helix-is rotated from a point where thel expansion of the bellows for' a l degree heat change is represented by I, to a point where the expansion for a l degree heat change is represented by 2, then the contact point between the helix and lever 33 should be. in the latter case, twice as far from the pivot 36. Thus it will be seen that the length of the levers. the pitch of the helix and the graduations on the drum are correlated and are applicable to all liquids that have substantially the same ratio of vapor expansion. However, for different liquidsthat is, where a different range of regulation is required, there will be a slightly different setting of the angularity of the arm, and this will be determined by test, hereafter explained. It should be understood that the gradual increase in the gap between the helix and the lever is provided to compensate for the known increase in the thickness of the bellows at increasing temperatures.

inasmuch as the ratio of vapor pressure increase of volatile liquids such as contemplated for use in this instrument is substantially uniform, the same helix having a desired pitch may be used for all such liquidsl and, a liquid being selected in the factory that will furnish proper regulation within a desired ra-nge, the instrument is rst adjusted so that at a temperature corresponding to the low limit of the range, the helix at a point near its upper end is in contact with the arm 33 and the valve I3 is closed. Then, from tests based on the spring resistance tc expansion by the bellows, it is determined that the total expansion of the bellows from the low point of the range to the high point of the range will amount to a certain measurement, say for example t/8 inch. 'Ihe angle of the arm 33 is then adjusted so that at a point near the lower end of the helix the gap between the edge oi' the helix and the arm 33 is 1A; inch. Then if by test it is found that the actual temperature does not exactly correspond to the reading on the drum the angle of the arm may be changed slightly to compensate or the screw 32 may be adjusted to change the spacing between the bellows and the helix. Thus by adjusting the instrument so that the range is secured well within the ends oi the helix there is provision for regulation both above and below the predetermined limits. In the case of adjustment for a much lower rangesay 50 to 150 degrees-the same procedure is followed. It is found, however, that at the upper limit of the range, with the particular liquid employed, the expansion of the bellows is but 11e inch. Therefore, the angle of the arm 33 is adjusted so that at a point near the lower end of the helix there is a gap of but 11g inch. and the drum is `adjusted on the helix shaft to indicate the correct temperature at that position of the helix. This explanation will make clear the statements in the specication and claims that the adjustment of the angle of the arm 33 is to permit range variation or changes in the range.

By the use of the described instrument a wide range of adjustment may be secured and the same instrument may be used for different ranges of temperatures, the latter result being secured by varying the character of the volatile liquid used in the bulb. The instrument can be immediately changed from quick acting to gradual acting; any diillculty due to hunting can be easily corrected, a wide range of adjustment up to 100 degrees can be secured as desired,and a graduated indicating drum or dial may be used in which the graduations are uniform, all in an instrument in which a volatile liquid is used as the thermally sensitive medium.

In the claims the term fulcrum point is used, in the absence of a better term, to describe the point of Contact between the helix 3D and the lever 33. Although the term is not strictly correct, the fact is that both said elements are pivoted for rockingv movement and one is rocked by the other through engagement of these contact points.

I claim:

l. In a thermostatic regulator, the combination of a bellows adapted to be influenced by the pressure of a thermally reacting uid, a valve for controlling a supply of a regulating fluid, levers for transmitting the movement of the bellows to the valve, means associated with said levers for progressively changing the ratio of the leverage according to the predetermined variation in pressure per degree of heat change therein of the thermally reacting fluid and means whereby the movement of the fulcrum-changing means acts to vary the effective separation of the valve and bellows, whereby to eiect an equal movement of said valve per degree of heat change throughout substantially the entire range of temperature control for which the instrument ls designed.

2. In a thermostatic regulator, the combination of a bellows adapted to be influenced by the pressure of a thermally reacting uid, a valve .for controlling a supply of a regulating fluid, levers for transmitting the movement of the bellows to the valve, means in the levers for changing a fulcrum point to compensate for variations in the vapor pressure per degree of heat change of the said thermal fluid and means whereby the movement of the lever-ratio-changing means acts to vary the effective separation of the valve and bellows, whereby to effect a substantially equal movement of said valve at all points in the control range of said regulator.

3. In a thermostatic regulator ofthe type employing a bulb containing a volatile fluid, the combination of a bellows influenced by said fluid, a valve for controlling a supply'of regulating fluid, levers for transmitting the movement of the bellows to the valve, adjusting means for changing the leverage, said adjusting means including a rotatable element having a helix thereon, said helix constituting a shiftable fulcrum point between two said levers, and means whereby the rotation of the helix acts to vary the effective separation of the valve and bellows whereby the movement of said valve per degree of heat change is substantially uniform throughout the range of control.

4. In a thermostatic regulator of the type employing a bulb containing a volatile fluid, the combination of a bellows influenced by said fluid, a valve for controlling a supply of regulating fluid, levers for transmitting the movement of the bellows tothe valve, adjusting means for changing the leverage, said adjusting means including a helix rotatable on an axis parallel to one of said levers, said helix constituting a variable fulcrum point, for the purpose described.

5, In a thermostatic regulator of the type em'- ploying a bulb containing a volatile fluid, the combination of a bellows influenced by said fluid, a valve for controlling a supply of regulating fluid, levers for transmitting the movement of the bellows to the valve, adjusting means for changing the leverage, said adjusting means including a helix rotatable on an axis, parallel to one of said levers, said helix constituting a variable fulcrum point, an auxiliary lever adapted to be directly contacted by said helix, and means for adjusting the position of said auxiliary lever whereby to change the range of adjustment of said device.

6. In a thermostatic regulator of the type employing a bulb containing a volatile fluid, the combination of a bellows influenced by said fluid, a valve for controlling a supply regulating fluid, levers for transmitting the movement of the bellows to the valve, adjusting means for changing the leverage, said adjusting means including a helix rotatable on an axis, parallel to one of said levers, said helix constituting a variable fulcruxn point, for the purpose described, and an auxiliary lever fulcrumed at one end and adjustable at its opposite end to change its angle, said auxiliary lever lying along side of and adapted to be contacted by said helix.

7. In a thermostatic regulation, the combination of a bellows -adapted to be influenced by the pressure of a thermostatic fluid, a leak valve for controlling a supply of a regulating fluid, means for transmitting the movement of said bellows to said leak valve, a second bellows open to the pressure of said regulating fluid after it passes said leak valve, means connecting said second bellows to the connecting means between said first named bellows and said leak valve and positioned so that expansion of said second bellows opposes the action of said rst bellows tending to close said valve, and adjusting means in said connection whereby to change the effective action of said second bellows to effect a predetermined result.

8. In a thermostatic regulator, the combination of a bellows adapted to be influenced by the pressure of a thermostatic fluid, a valve for controlling a supply of a regulating fluid, levers for transmitting the movement of the bellows to the valve, a second bellows open to the pressure of the regulating fluid after it passes said valve, said second bellows being positioned to oppose the action of one of said levers tending to move said valve under the influence of said first bellows and adjusting means in the connection between said second bellows and said lever, whereby said second bellows may be rendered ineffective and thereby enable quick action of the regulating fluid, or, selectively, made effective to bring about gradual action by said reguating fluid.

9. In combination, a bellows, a leak valve for controlling the delivery of air under pressure to a heat valve, a lever connecting the bellows to the ilrst named valve, a second bellows positioned to oppose .movement of said lever tending to close said leak valve, said second bellows being open to the air after it passes said leak valve, and adjusting means in the connection between said lever and said second bellows, whereby said second bellows may be made effective or ineffective to secure a predetermined result.

ll/IORTON O. SNEDIKER. 

